Polyimide film having improved breakdown characteristics and method for manufacturing same

Abstract

The present invention provides a polyimide film comprising: a polyimide comprising, as repeating units, an anhydride monomer and a diamine monomer; and nanoparticles having an average particle size of 100 to 500 nm, wherein the polyimide film has a breakdown voltage (BDV) of 350 kV / mm or more and a surface roughness (Ra) value of 0.01 nm or more.

Description

Polyimide film with improved insulation breakdown characteristics and its manufacturing method

[0001] The present invention relates to a polyimide film with improved insulation breakdown characteristics and a method for manufacturing the same. More particularly, the present invention relates to a polyimide film with improved insulation breakdown characteristics by including nanoparticles having an average particle size of 100 to 500 nm, and a method for manufacturing the same.

[0002] In general, polyimide (PI) film is a film made of polyimide resin. Polyimide resin is a high-heat-resistant resin manufactured by solution polymerizing an aromatic dianhydride and an aromatic diamine or an aromatic diisocyanate to produce a polyamic acid derivative, and then imidizing it by ring-closing dehydration at high temperatures.

[0003] Polyimide resin is an insoluble, non-melting, ultra-high heat-resistant resin with a high glass transition temperature, excellent heat-oxidation resistance, heat resistance, radiation resistance, low-temperature characteristics, chemical resistance, and electrical properties. Due to this, it is used in various forms such as films, resins, molded parts, adhesives, and insulators in the electrical, electronic, automotive, and aerospace industries. In particular, as an electronic material, its insulation properties and thermal and chemical stability are excellent, and its use is expanding to include interlayer insulating films for semiconductor chips.

[0004] Among the various applications, polyimide films used in secondary batteries require high breakdown voltage (BDV) as a key physical property. Furthermore, breakdown resistance is proportional to film thickness. Films with higher breakdown voltage per unit thickness can meet the required breakdown voltage at lower thicknesses, enabling smaller and lighter films. Furthermore, securing the required roughness using fillers is essential for ensuring sample rollability during the roll-to-roll process of polyimide films.

[0005] Therefore, there is a need to develop a polyimide film that satisfies both the required illumination and the enhanced breakdown voltage.

[0006] The purpose of the present invention is to provide a polyimide film having improved insulation breakdown characteristics and satisfying the required roughness for securing the windability of a sample, and a method for manufacturing the same.

[0007] In addition, the present invention aims to provide a secondary battery including the polyimide film.

[0008] The present invention is susceptible to various modifications and embodiments. Therefore, specific embodiments are illustrated and described in detail. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0009] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0010] When amounts, concentrations, or other values ​​or parameters are given herein as a range, preferred range, or enumeration of an upper preferred value and a lower preferred value, it should be understood that this specifically discloses any range formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed.

[0011] When a range of numerical values ​​is mentioned in this specification, unless otherwise stated, it is intended that the endpoints of the range and the scope of the invention within the range are not limited to the specific values ​​mentioned in defining the range.

[0012] As used herein, "dianhydride" is intended to include precursors or derivatives thereof, also referred to as "dianhydric acids," "dianhydrides," or "acid dianhydrides." While these may not technically be dianhydrides, they will nonetheless react with diamines to form polyamic acids, which can then be converted to polyimides.

[0013] As used herein, "diamine" is intended to include precursors or derivatives thereof, which may not technically be diamines, but which will nonetheless react with a dianhydride acid to form a polyamic acid, which in turn can be converted to a polyimide.

[0014] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be construed in an idealized or overly formal sense unless explicitly defined herein. Specific details for implementing the invention are described below.

[0015] The present invention relates to a polyimide film with improved insulation breakdown characteristics and a method for manufacturing the same.

[0016] polyimide film

[0017] The present invention provides a polyimide film comprising a polyimide comprising a dianhydride monomer and a diamine monomer as polymerization units; and nanoparticles having an average particle size of 100 to 500 nm, and having a breakdown voltage (BDV) of 350 kV / mm or more and a roughness (Ra) value of 0.01 nm or more.

[0018] The average particle size of the nanoparticles may be 100 to 500 nm, preferably 100 nm or more and less than 500 nm, more preferably 110 to 400 nm, 120 to 350 nm, 130 to 300 nm, 135 to 290 nm, 140 to 280 nm, 145 to 270 nm, 148 to 260 nm, and even more preferably 150 to 250 nm. When the average particle size of the nanoparticles is less than 100 nm, the roughness (Ra) value is low, which is undesirable, and when it exceeds 500 nm, the issue of dispersion of the nanoparticles within the film may occur, which is undesirable.

[0019] In one embodiment, the average particle size of the nanoparticles can be measured using a Laser Diffraction Particle Size Analyzer (SHIMADZU, Model SALD-2201).

[0020] The breakdown voltage (BDV) of the above polyimide film may be 350 kV / mm or more, and for example, the lower limit of the breakdown voltage may be 353 kV / mm, 355 kV / mm, 358 kV / mm, or 360 kV / mm or more. The upper limit of the breakdown voltage is not particularly limited, but may be 500 kV / mm or less, 400 kV / mm or less, 350 kV / mm or less, 330 kV / mm or less, or 320 kV / mm or less.

[0021] The above breakdown voltage (BDV) can be measured using a method known in the industry. In one example, the breakdown voltage can be measured according to the ASTM D149 standard. Specifically, the polyimide film is pretreated in an oven at 100°C to remove moisture, and then fixed to a measuring device (PHENIX TECHNOLOGIES 6CCE50-5) set to a room temperature atmosphere, and a voltage of 10 KVAc is applied from the upper and lower electrodes to increase the AC voltage from 0 at a constant rate, thereby measuring the BDV.

[0022] The roughness (Ra) value of the above polyimide film may be 0.01 nm or more, and for example, the lower limit of the roughness (Ra) value may be 0.0105 nm, 0.0108 nm, 0.0110 nm, 0.0115 nm, 0.0118 nm, or 0.012 nm or more. The upper limit of the roughness (Ra) value is not particularly limited, but may be 0.05 nm or less, 0.04 nm or less, 0.035 nm or less, or 0.03 nm or less.

[0023] The above roughness (Ra) refers to the arithmetic mean roughness and can be measured using a method known in the industry. In one example, the above roughness (Ra) can be measured using a film roughness analyzer from Kosaka Laboratory Ltd.

[0024] The above nanoparticles may include nanosilica.

[0025] The polyimide film may contain 1,000 to 5,000 ppm of the nanoparticles, preferably 1,500 to 4,500 ppm, 1,800 to 4,200 ppm, 2,000 to 4,000 ppm, 2,300 to 3,700 ppm, 2,500 to 3,500 ppm, and more preferably 2,800 to 3,200 ppm.

[0026] If the polyimide film contains less than 1,000 ppm of the nanoparticles, the breakdown voltage value is low, which is not desirable. If it contains more than 5,000 ppm, the improvement in breakdown voltage is minimal compared to the nanoparticles used, which is not desirable because it is inefficient.

[0027] The above dianhydride monomers are pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), biphenyl tetracarboxylic dianhydride (BPDA), oxydiphthalic dianhydride (ODPA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianhydride (DSDA), bis(3,4-dicarboxyphenyl)sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-Phenylenebis(trimellitic monoester acid anhydride), p-Biphenylenebis(trimellitic monoester acid anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3-Bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-Bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-Bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-Bis〔(3,4-dicarboxyphenoxy)phenyl〕propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic It may include at least one selected from the group consisting of dianhydride and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianhydride, and preferably pyromellitic dianhydride (PMDA).

[0028] The above diamine monomers are 1,4-diaminobenzene (PPD), 4,4'-diaminodiphenyl ether (ODA), 2,2-bisaminophenoxyphenylpropane (BAPP), metaphenylenediamine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (DABA), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-tolidine), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 4,4'-diaminobenzanilide, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3,3'-Diaminodiphenylmethane, 3,4'-Diaminodiphenylmethane, 4,4'-Diaminodiphenylmethane, 2,2-Bis(3-aminophenyl)propane, 2,2-Bis(4-aminophenyl)propane, 2,2-Bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-Bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-Diaminodiphenylsulfoxide, 3,4'-Diaminodiphenylsulfoxide, 4,4'-Diaminodiphenylsulfoxide, 1,3-Bis(3-aminophenyl)benzene, 1,3-Bis(4-aminophenyl)benzene, 1,4-Bis(3-aminophenyl)benzene, 1,4-Bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,4-bis(3-aminophenoxy)benzene (TPE-Q), 1,3-bis(3-aminophenoxy)-4-trifluoromethylbenzene, 3,3'-Diamino-4-(4-phenylphenoxy)benzophenone, 3,3'-diamino-4,4'-di(4-phenylphenoxy)benzophenone, 1,3-bis(3-aminophenylsulfide)benzene, 1,3-bis(4-aminophenylsulfide)benzene, 1,4-bis(4-aminophenylsulfide)benzene, 1,3-bis(3-aminophenylsulfone)benzene, 1,3-bis(4-aminophenylsulfone)benzene, 1,4-bis(4-aminophenylsulfone)benzene, 1,3-bis〔2-(4-aminophenyl)isopropyl〕benzene, 1,4-bis〔2-(3-aminophenyl)isopropyl〕benzene, 1,4-bis〔2-(4-aminophenyl)isopropyl〕benzene, 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-Bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis〔3-(3-aminophenoxy)phenyl〕ether, bis〔3-(4-aminophenoxy)phenyl〕ether, bis〔4-(3-aminophenoxy)phenyl〕ether, bis〔4-(4-aminophenoxy)phenyl〕ether, bis〔3-(3-aminophenoxy)phenyl〕ketone, bis〔3-(4-aminophenoxy)phenyl〕ketone, bis〔4-(3-aminophenoxy)phenyl〕ketone, bis〔3-(3-aminophenoxy)phenyl〕sulfide, bis〔3-(4-aminophenoxy)phenyl〕sulfide, Bis〔4-(3-aminophenoxy)phenyl〕sulfide, bis〔4-(4-aminophenoxy)phenyl〕sulfide, bis〔3-(3-aminophenoxy)phenyl〕sulfone, bis〔3-(4-aminophenoxy)phenyl〕sulfone, bis〔4-(3-aminophenoxy)phenyl〕sulfone, bis〔4-(4-aminophenoxy)phenyl〕sulfone, bis〔3-(3-aminophenoxy)phenyl〕methane, bis〔3-(4-aminophenoxy)phenyl〕methane, bis〔4-(3-aminophenoxy)phenyl〕methane, bis〔4-(4-aminophenoxy)phenyl〕methane, 2,2-bis〔3-(3-aminophenoxy)phenyl〕propane, 2,2-bis〔3-(4-aminophenoxy)phenyl〕propane, 2,2-bis〔4-(3-aminophenoxy)phenyl〕propane, 2,2-bis〔3-(3-aminophenoxy)phenyl〕-1,1,1,3,3,3-hexafluoropropane, 2,2-bis〔3-(4-aminophenoxy)phenyl〕-1,1,1,3,3,3-hexafluoropropane, 2,It may include at least one selected from the group consisting of 2-bis〔4-(3-aminophenoxy)phenyl〕-1,1,1,3,3,3-hexafluoropropane and 2,2-bis〔4-(4-aminophenoxy)phenyl〕-1,1,1,3,3,3-hexafluoropropane, and preferably may include 1,4-diaminobenzene (PPD) and 4,4'-diaminodiphenyl ether (ODA).

[0029] In one embodiment, the 1,4-diaminobenzene (PPD) content in the total diamine monomers may be greater than 0 mol% and less than or equal to 50 mol%. For example, the upper limit may be less than or equal to 48 mol%, less than or equal to 45 mol%, less than or equal to 43 mol%, less than or equal to 40 mol%, less than or equal to 38 mol%, less than or equal to 35 mol%, less than or equal to 32 mol%, or less than or equal to 30 mol%, and the lower limit may be greater than or equal to 1 mol%, greater than or equal to 2 mol%, greater than or equal to 3 mol%, greater than or equal to 4 mol%, greater than or equal to 5 mol%, greater than or equal to 6 mol%, greater than or equal to 7 mol%, greater than or equal to 8 mol%, greater than or equal to 9 mol%, greater than or equal to 10 mol%, greater than or equal to 12 mol%, greater than or equal to 14 mol%, greater than or equal to 16 mol%, greater than or equal to 18 mol%, or greater than or equal to 20 mol%. Preferably, the content of 1,4-diaminobenzene (PPD) among the total diamine monomers may be 20 to 30 mol%.

[0030] When the above 1,4-diaminobenzene (PPD) content exceeds 50 mol%, heat resistance increases, but the manufactured film becomes brittle, which is not desirable. On the other hand, when the above 1,4-diaminobenzene (PPD) content is 0 mol%, heat resistance is low, which is not desirable.

[0031] In one embodiment, the 4,4'-diaminodiphenyl ether (ODA) content in the total diamine monomer may be 50 mol% or more and less than 100 mol%. For example, the upper limit may be 99 mol% or less, 98 mol% or less, 97 mol% or less, 96 mol% or less, 95 mol% or less, 94 mol% or less, 93 mol% or less, 92 mol% or less, 91 mol% or less, 90 mol% or less, 88 mol% or less, 86 mol% or less, 84 mol% or less, 82 mol% or less, or 80 mol% or less, and the lower limit may be 52 mol% or more, 55 mol% or more, 57 mol% or more, 60 mol% or more, 62 mol% or more, 65 mol% or more, 68 mol% or more, or 70 mol% or more. Preferably, the content of 4,4'-diaminodiphenyl ether (ODA) among the total diamine monomers may be 70 to 80 mol%.

[0032] When the content of the above 4,4'-diaminodiphenyl ether (ODA) is less than 50 mol%, the heat resistance increases, but the manufactured film becomes brittle, which is not preferable. On the other hand, when the content of the above 4,4'-diaminodiphenyl ether (ODA) is 100 mol%, the flexibility (elongation) of the film increases, but the heat resistance decreases (Tg decreases), which is not preferable.

[0033] The molar ratio of the above-mentioned dihydric acid monomer and the above-mentioned diamine monomer may be 1:2 to 2:1, and preferably 1:1.

[0034] The polyimide may contain 90 to 110 mol% of the diamine monomer, preferably 95 to 105 mol%, more preferably 98 to 102 mol%, and even more preferably 99 to 101 mol%.

[0035] The polyimide may contain 90 to 110 mol% of the dianhydride monomer, preferably 95 to 105 mol%, more preferably 98 to 102 mol%, and even more preferably 100 mol%.

[0036] The polyimide may have 95 to 105 mol% of the dianhydride monomer based on 100 mol% of the diamine monomer, and for example, the lower limit may be 95.5 mol% or more, 96 mol% or more, 96.5 mol% or more, 97 mol% or more, 97.5 mol% or more, 98 mol% or more, 98.5 mol% or more, 99 mol% or more, or 99.5 mol% or more, and the upper limit may be 105 mol% or less, 104 mol% or less, 103 mol% or less, 102 mol% or less, 101 mol% or less, or 100 mol% or less.

[0037] The thickness of the above polyimide film can be appropriately selected considering the purpose, usage environment, physical properties, etc. of the polyimide film. For example, the thickness of the polyimide film can be 1 to 100 μm, 15 to 70 μm, 25 to 50 μm, or 30 to 45 μm, but is not limited thereto.

[0038] Another embodiment of the present invention provides a secondary battery including the polyimide film.

[0039] Method for manufacturing polyimide film

[0040] Hereinafter, a method for manufacturing a polyimide film is described. The method for manufacturing a polyimide film according to the present invention is described excluding any content that overlaps with the content of the polyimide film described above. However, the content described in the polyimide film described above also applies equally to the method for manufacturing a polyimide film described below.

[0041] The present invention provides a method for producing a polyimide film, comprising the steps of: (a) preparing a polyamic acid solution by adding an dianhydride monomer and a diamine monomer to a solvent and subjecting them to an imidization reaction; (b) preparing a mixed solution by adding nanoparticles having an average particle size of 100 to 500 nm to the polyamic acid solution and stirring the mixture; and (c) applying and drying the mixed solution to produce a polyimide film; wherein the breakdown voltage (BDV) of the polyimide film is 350 kV / mm or more and the roughness (Ra) value of the polyimide film is 0.01 nm or more.

[0042] The above mixed solution may contain 1,000 to 5,000 ppm of the nanoparticles, preferably 1,500 to 4,500 ppm, 1,800 to 4,200 ppm, 2,000 to 4,000 ppm, 2,300 to 3,700 ppm, 2,500 to 3,500 ppm, and more preferably 2,800 to 3,200 ppm.

[0043] If the above mixed solution contains less than 1,000 ppm of the nanoparticles, the breakdown voltage value of the manufactured polyimide film is low, which is not desirable, and if it exceeds 5,000 ppm, the improvement in breakdown voltage is minimal compared to the nanoparticles used, which is inefficient, which is not desirable.

[0044] The solvent may include at least one selected from the group consisting of N,N'-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N,N'-dimethylformamide (DMF), dimethylsulfoxide (DMSO), diethylacitamide (DEAc), N-ethyl-2-pyrrolidone (NEP), N,N'-diethylformamide (DEF), dimethylpropanamide (DMPA), and gamma-butyrolactone (GBL).

[0045] In the present invention, the polyamic acid solution may have a solid content of 15 to 50 wt% based on 100 parts by weight of the polyamic acid solution. The lower limit of the solid content by weight may be 16, 17, 18, 19, or 20 wt% or more, and the upper limit of the solid content by weight may be 45, 40, 35, 30, 27, or 25 wt% or less. By controlling the solid content of the polyamic acid solution, the increase in viscosity can be controlled and the process time in the curing process can be shortened.

[0046] Another embodiment of the present invention provides a secondary battery including a polyimide film manufactured by the method for manufacturing the polyimide film.

[0047] The polyimide film and its manufacturing method according to the present invention have the effect of improving electrical properties by enhancing the breakdown strength and improving the breakdown voltage by including nanoparticles having an average particle size of 100 to 500 nm, thereby increasing the practicality of the film for secondary batteries.

[0048] In addition, the polyimide film and its manufacturing method according to the present invention have the effect of satisfying the required roughness for securing the windability of a sample in a roll-to-roll process.

[0049] In addition, the polyimide film according to the present invention has an effect that can be applied to secondary batteries.

[0050] To aid in understanding the present invention, examples are presented. The following examples are provided solely to facilitate a better understanding of the present invention, and the scope of the present invention is not limited by the examples.

[0051] <Example: Manufacturing of polyimide film>

[0052] Example

[0053] A polyamic acid solution was prepared by mixing 100 mol% of a diamine monomer and 100 mol% of a dianhydride monomer into 100 mol% of a solvent, dimethylformamide (DMF). At this time, the diamine monomer includes 25 mol% of 1,4-diaminobenzene (PPD) and 75 mol% of 4,4'-diaminodiphenyl ether (ODA), and the dianhydride monomer includes 100 mol% of pyromellitic dianhydride (PMDA).

[0054] A mixed solution was prepared by adding 3,000 ppm of nanosilica with an average particle size of 100 nm and a catalyst to the above polyamic acid solution and stirring.

[0055] The above-described mixed solution was applied to a glass plate. Subsequently, the solvent-to-solids ratio was calculated using an applicator, and the solution was evenly distributed across the surface. The polyimide film was then cured at 130°C (3 minutes) → 280°C (4 minutes) → 420°C (4 minutes). The film thickness was 12.5 μm.

[0056] Examples 2 to 5

[0057] A polyimide film was manufactured in the same manner as in Example 1, except that the average particle size of nanosilica was used differently, as shown in Table 1 below.

[0058] Comparative Examples 1 to 4

[0059] A polyimide film was manufactured in the same manner as in Example 1, except that calcium phosphate was used instead of nanosilica as shown in Table 1 below, and the average particle size and content of calcium phosphate were used differently.

[0060] Comparative Examples 5 to 7

[0061] A polyimide film was manufactured in the same manner as in Example 1, except that the average particle size of nanosilica was used differently, as shown in Table 1 below.

[0062] Table 1 below shows the types, average particle sizes, and contents of nanoparticles (nanosilica, calcium phosphate) used in manufacturing polyimide films according to Examples 1 to 5 and Comparative Examples 1 to 7.

[0063] ClassificationNano particle typeAverage particle sizeContent (ppm)Example 1Nano silica100 nm3,000Example 2Nano silica150 nm3,000Example 3Nano silica200 nm3,000Example 4Nano silica250 nm3,000Example 5Nano silica500 nm3,000Comparative example 1Calcium phosphate2 ㎛1,000Comparative example 2Calcium phosphate2 ㎛2,000Comparative example 3Calcium phosphate1 ㎛1,000Comparative example 4Calcium phosphate1 ㎛2,000Comparative example 5Nano silica20 nm3,000Comparative example 6Nano silica50 nm3,000Comparative example 7Nano silica90 nm3,000

[0064] <Experimental Example: Evaluation of Physical Properties of Polyimide Film>

[0065] Experimental Example 1. Evaluation of Insulation Breakdown Voltage (BDV)

[0066] The breakdown voltage (BDV) values ​​of the polyimide films manufactured in the above examples and comparative examples were measured according to the ASTM D149 standard. Specifically, the polyimide films were pretreated in an oven at 100°C to remove moisture, and then fixed to a measuring device (PHENIX TECHNOLOGIES 6CCE50-5) set to a room temperature atmosphere, and a voltage of 10 KVAc was applied from the upper electrodes of the lower part to increase the AC voltage from 0 at a constant rate to measure the BDV. The measurement results are shown in Table 2 below.

[0067] Experimental Example 2. Measurement of roughness (Ra) values

[0068] The roughness (Ra) values ​​of the polyimide films manufactured in the above examples and comparative examples were measured using a film roughness analyzer from Kosaka Laboratory Ltd. The measurement results are shown in Table 2 below.

[0069] Classification BDV (kV / mm) Illumination (Ra) (nm) Example 13580.011 Example 23620.012 Example 33630.014 Example 43630.015 Example 53500.017 Comparative Example 12880.028 Comparative Example 23100.028 Comparative Example 32970.021 Comparative Example 43030.021 Comparative Example 53000.005 Comparative Example 63600.006 Comparative Example 73510.009

[0070] According to Table 2, it can be confirmed that Examples 1 to 5 using nanosilica having an average particle size of 100 to 500 nm all have excellent BDV values ​​(≥350 kV / mm) and roughness (Ra) values ​​(≥0.010 nm).

[0071] Meanwhile, it can be confirmed that comparative examples 1 to 4 using calcium phosphate with an average particle size of 1 ㎛ and 2 ㎛ have excellent roughness (Ra) values ​​but low BDV values.

[0072] Additionally, it can be confirmed that comparative examples 5 to 7 using nanosilica having an average particle size of less than 100 nm have low roughness values.

[0073] On the other hand, Example 5 using nano-silica with an average particle size of 500 nm has excellent BDV values ​​(≥350 kV / mm) and roughness (Ra) values ​​(≥0.010 nm), but is not desirable because filler dispersion issues may occur.

[0074] From these results, the polyimide film of the present invention and its manufacturing method can improve the electrical properties by enhancing the breakdown voltage by strengthening the dielectric breakdown strength by including nanoparticles having an average particle size of 100 to 500 nm, thereby increasing the practicality of the film for secondary batteries.

[0075] In addition, the polyimide film and its manufacturing method according to the present invention have the effect of satisfying the required roughness for securing the windability of a sample in a roll-to-roll process by including nanoparticles having an average particle size of 100 to 500 nm.

[0076] In addition, the polyimide film according to the present invention has an effect that can be applied to secondary batteries.

[0077] The specification omits detailed descriptions of matters that would be readily apparent and inferred by those skilled in the art. Furthermore, various modifications, other than the specific examples described herein, are possible without altering the technical spirit or essential configuration of the invention. Therefore, the present invention may be practiced in ways other than those specifically described and exemplified herein, as will be readily apparent to those skilled in the art.

Claims

1. Polyimide containing an dianhydride monomer and a diamine monomer as polymerization units; and Comprising nanoparticles having an average particle size of 100 to 500 nm; The breakdown voltage (BDV) is 350 kV / mm or more, A polyimide film having a roughness (Ra) value of 0.01 nm or more.

2. In paragraph 1, A polyimide film wherein the above nanoparticles contain nanosilica.

3. In paragraph 1, A polyimide film, wherein the polyimide film contains 1,000 to 5,000 ppm of the nanoparticles.

4. In paragraph 1, The above dianhydride monomers are pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), biphenyl tetracarboxylic dianhydride (BPDA), oxydiphthalic dianhydride (ODPA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianhydride (DSDA), bis(3,4-dicarboxyphenyl)sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-Phenylenebis(trimellitic monoester acid anhydride), p-Biphenylenebis(trimellitic monoester acid anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3-Bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-Bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-Bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-Bis〔(3,4-dicarboxyphenoxy)phenyl〕propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic A polyimide film comprising at least one selected from the group consisting of dianhydride and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianhydride.

5. In paragraph 4, A polyimide film, wherein the above-mentioned dihydride monomer comprises pyromellitic dianhydride (PMDA).

6. In paragraph 1, The above diamine monomers are 1,4-diaminobenzene (PPD), 4,4'-diaminodiphenyl ether (ODA), 2,2-bisaminophenoxyphenylpropane (BAPP), metaphenylenediamine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (DABA), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-tolidine), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 4,4'-diaminobenzanilide, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3,3'-Diaminodiphenylmethane, 3,4'-Diaminodiphenylmethane, 4,4'-Diaminodiphenylmethane, 2,2-Bis(3-aminophenyl)propane, 2,2-Bis(4-aminophenyl)propane, 2,2-Bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-Bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-Diaminodiphenylsulfoxide, 3,4'-Diaminodiphenylsulfoxide, 4,4'-Diaminodiphenylsulfoxide, 1,3-Bis(3-aminophenyl)benzene, 1,3-Bis(4-aminophenyl)benzene, 1,4-Bis(3-aminophenyl)benzene, 1,4-Bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,4-bis(3-aminophenoxy)benzene (TPE-Q), 1,3-bis(3-aminophenoxy)-4-trifluoromethylbenzene, 3,3'-Diamino-4-(4-phenylphenoxy)benzophenone, 3,3'-diamino-4,4'-di(4-phenylphenoxy)benzophenone, 1,3-bis(3-aminophenylsulfide)benzene, 1,3-bis(4-aminophenylsulfide)benzene, 1,4-bis(4-aminophenylsulfide)benzene, 1,3-bis(3-aminophenylsulfone)benzene, 1,3-bis(4-aminophenylsulfone)benzene, 1,4-bis(4-aminophenylsulfone)benzene, 1,3-bis〔2-(4-aminophenyl)isopropyl〕benzene, 1,4-bis〔2-(3-aminophenyl)isopropyl〕benzene, 1,4-bis〔2-(4-aminophenyl)isopropyl〕benzene, 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-Bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis〔3-(3-aminophenoxy)phenyl〕ether, bis〔3-(4-aminophenoxy)phenyl〕ether, bis〔4-(3-aminophenoxy)phenyl〕ether, bis〔4-(4-aminophenoxy)phenyl〕ether, bis〔3-(3-aminophenoxy)phenyl〕ketone, bis〔3-(4-aminophenoxy)phenyl〕ketone, bis〔4-(3-aminophenoxy)phenyl〕ketone, bis〔3-(3-aminophenoxy)phenyl〕sulfide, bis〔3-(4-aminophenoxy)phenyl〕sulfide, Bis〔4-(3-aminophenoxy)phenyl〕sulfide, bis〔4-(4-aminophenoxy)phenyl〕sulfide, bis〔3-(3-aminophenoxy)phenyl〕sulfone, bis〔3-(4-aminophenoxy)phenyl〕sulfone, bis〔4-(3-aminophenoxy)phenyl〕sulfone, bis〔4-(4-aminophenoxy)phenyl〕sulfone, bis〔3-(3-aminophenoxy)phenyl〕methane, bis〔3-(4-aminophenoxy)phenyl〕methane, bis〔4-(3-aminophenoxy)phenyl〕methane, bis〔4-(4-aminophenoxy)phenyl〕methane, 2,2-bis〔3-(3-aminophenoxy)phenyl〕propane, 2,2-bis〔3-(4-aminophenoxy)phenyl〕propane, 2,2-bis〔4-(3-aminophenoxy)phenyl〕propane, 2,2-bis〔3-(3-aminophenoxy)phenyl〕-1,1,1,3,3,3-hexafluoropropane, 2,2-bis〔3-(4-aminophenoxy)phenyl〕-1,1,1,3,3,3-hexafluoropropane, 2,A polyimide film comprising at least one selected from the group consisting of 2-bis〔4-(3-aminophenoxy)phenyl〕-1,1,1,3,3,3-hexafluoropropane and 2,2-bis〔4-(4-aminophenoxy)phenyl〕-1,1,1,3,3,3-hexafluoropropane.

7. In paragraph 6, A polyimide film wherein the above diamine monomer comprises 1,4-diaminobenzene (PPD) and 4,4'-diaminodiphenyl ether (ODA).

8. In paragraph 7, Among the total diamine monomers, the content of 1,4-diaminobenzene (PPD) is greater than 0 mol% and less than or equal to 50 mol%, A polyimide film, wherein the content of 4,4'-diaminodiphenyl ether (ODA) among the total diamine monomers is 50 mol% or more and less than 100 mol%.

9. In paragraph 1, A polyimide film having a thickness of 1 to 100 μm.

10. A secondary battery comprising a polyimide film according to paragraph 1. 11.(a) A step of preparing a polyamic acid solution by adding an dianhydride monomer and a diamine monomer to a solvent and polymerizing them; (b) a step of preparing a mixed solution by adding nanoparticles having an average particle size of 100 to 500 nm to the polyamic acid solution and stirring; and (c) a step of applying and drying the above mixed solution to manufacture a polyimide film; The breakdown voltage (BDV) of the above polyimide film is 350 kV / mm or more, A method for manufacturing a polyimide film, wherein the polyimide film has a roughness (Ra) value of 0.01 nm or more.

12. In paragraph 11, A method for manufacturing a polyimide film, wherein the mixed solution contains 1,000 to 5,000 ppm of the nanoparticles.

13. In paragraph 11, A method for manufacturing a polyimide film, wherein the solvent comprises at least one selected from the group consisting of N,N'-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N,N'-dimethylformamide (DMF), dimethylsulfoxide (DMSO), diethylacitamide (DEAc), N-ethyl-2-pyrrolidone (NEP), N,N'-diethylformamide (DEF), dimethylpropanamide (DMPA), and gamma-butyrolactone (GBL).